Stencil sheet



, Patented Aug. 3, 1926.

UNITED. sr'ras JACOB BILSKY, OF CHICAGO, ILLHVOIS, ASSIGNOR TO A; B.DICK COMPANY, OF CHICAGO,

PATENT OFFICE.

. rumors, A ooaromrrou or iinmors.

STENCIL SHEET.

Io Drawing.

The object of this invention is to produce a stencil sheet suitable foruse on duplicating machines commonly in use, such as the mimeograph, andwhich shall improve upon sheets heretofore developed, particularly suchas have become known as indestructible stencil sheets, which requiremoistening as a preliminary to the stencilizing operation. In thisconnection, my object is to produce a stencil sheet not requirmg suchpreliminary moistenmg, but capable at all times of being stencilized inits normal condition. A further object is to produce a stencil sheetwhich may be readily and simply produced, which shall be capable of theuse indicated throughout an extended period of time, which shall havegreat durabilit and so be capable of producing a large number of copiesand which shall yield copies of a high degree of excellence.

In carrying out the invention, I employ a base of open, porous material,such as the bibulous Japanese paper commonly known as yoshino. This Iprovide with a coating consisting in the main of a cellulose ester, suchas nitro cellulose, in a suitable solvent, suchas a. mixture of alcoholand ether, combining therewith a substantial content of a fatty acid,such, for example, as oleic acid. I have found it desirable to use afour or five per cent solution of nitrocellulose insubstantially equalparts of alcohol and ether, adding to this (preferably) con merciallypure oleic acid to the extent of one-fifth to one-third the combinedcellulose and solvent above specified. 'As a preferred formula, I usesuch oleic. acid to the extent of approximately twenty per cent of thewhole solution.

In combining the materials above specified, I first proceedto producethe cellulosealcohol-ether solution and then add the oleid acid whilesuitably stirring or agitating the mixture, such acid being added insmall quantities as the stirrings or agitation roceeds. Thisoperation-being completed, the compound may be. applied to the yoshinosheet in any well known manner, as, for instance, that commonly employed.in the production of the socalled indestructible? sten- Gil sheets, i.e., the compound is placed-in 9.

Application filed June 80,

suitable tank or pan and the yoshino drawn over its-surface, excesssolution being removed by withdrawing the yoshino from the tank or pairin contact with a straightedge, mm or similar device.

While I have herein expressed a preference for the particular fattysubstance known as oleic acid, it may be notedthat I may, if desired,use, in place thereof,stearin or stearic acid, which, however, requiresmodlfication, since normally it is relatively hard and requires, tobring it to the requisite softness, the admixtureof other ingredients,among them being oleic acid, castor oil and the like. I may also usehydrogenated fatty acids or combinations thereof with oleic the coatedsheet, to add to the solution above described a small portion of asuitable gum, such, for example, as latex rubber, dissolved in asuitable solvent, such as tetralin. A one to three per cent solution oflatex rubber in tetralin has been found to answer the purpose, but othergums may be used to accomplish the same result. It will also beunderstood that if desirable for any purpose, as for cheapening thecompound or to attain the ri ht consistency for drawing the paper, maadd any suitable diluents such as oils, alco ol, 'toluol and the like.

Having now described my invention, what I claim is:

1. A stencil sheet adapted to be stencilized by pressure, comprising anopen, porous base having a coating including-a cellulose compound andoleic acid.

2. A stencil sheet adapted to be stencilized bypressure, comprising anopen, porous base havmg' a coatmg including a cellulose JACOB BILSKY.

